Transistor Ladder Filter panel

Seems like this might be a good time to split off a new topic.

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I think I’ve taken the idea far enough for now, apologies for the derail. My thinking on this needs time to mature.

I like the tweaks! I want one!

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love it! Want as well!! :smiley: if there are extras of course :slight_smile:

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Love the panel. Don’t change the font.
For me it’s not immediately clear where to put my jack with LFO output for cutoff and where for resonance, but I don’t know synthesis very well yet, so maybe that’s just me.

Both are for the cutoff frequency, but the v/oct has an exponential relation. So if you tune the Filter, you can play it like a vco! Then you can use the linear cv for vibrato or something :wink:
Resonance has no CV.


Sure! Not tested yet, so be patient :wink: I will order in a few days and then also put this on github.


Thank you for explanation.

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I wouldn’t count a module as finished until you’ve tested it. But that’s probably just the software developer in me speaking.

I suppose the difference is you can test it until you finish it. At least in a way.

Where did you pick up your BC557C? I found the 547s but no luck on the 5’s

DigiKey has the BC557CZL1, listed as obsolete but they have stock:

Tayda has the BC557B, which is a lower gain version than the BC557C. Might work.

The docs say in reference to the paired BC547C, “The specified transistor is BC547C, but most small-signal NPN transistors should work just fine.” No similar remarks about the BC557C, but that’s probably a good sign — having said you can sub the ladder transistors, if the expo converter transistors were critical they’d say so, right?


it can drive you crazy looking for parts . can’t find it , change one dam letter / number in your search and then there is a million of them .


Yeah, just try out any similar transistor you have around…

@klausklaerwerk used a 559C and it works:

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is there a BOM for this?
I just received one from @CTorp

Just look up the Kassutronics build guide/BOM. All of his guides are really great.


Thank ya good sir :slight_smile:

Except you have to buy 6,010 of the BC557CZLs…lol. I don’t think i want to be a BC557C store :upside_down_face:

EDIT: Mouser has BC547C’s for 7.6 cents at qty 100.


yeah I had to buy 200 @ 24.9k resistors the min. , of which I will use less than 6 and probably never touch the rest in this life time …

I’m just gonna use one of the 557Bs that i already have around. As far as the 547s the footnote was talking about using 2N3904s so I don’t think it’s really that important.

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